You’ve been diagnosed with knee osteoarthritis, which is the wearing away of articular cartilage—the cartilage that wraps the ends of bones in a joint and helps them glide smoothly together. Your orthopedic surgeon is recommending a knee replacement to alleviate your pain and stiffness. However, before you go under the knife, you should ask if you’re a candidate for a partial knee replacement.
What’s the difference between a partial knee replacement and a total knee replacement? How do you know which one is the best option for you? First, it’s necessary to understand the anatomy of the knee.\
Knee Anatomy 101
The knee consists of three compartments:
- Lateral compartment
- Medial compartment
- Patellofemoral compartment
The medial compartment is the section on the inside of the knee—the side closest to the other leg. The lateral compartment is on the outside, and the patellofemoral compartment is at the front of the knee, between the kneecap (patella) and thigh bone (femur).
The knee joint is a meeting of three bones: the patella (kneecap), the femur (thigh bone) and the tibia (shin bone). The knee is also held together by a number of ligaments:
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
- Lateral collateral ligament (LCL)
- Medial collateral ligament (MCL)
Additionally, two pads of cartilage called the menisci (singular meniscus) sit between the tibia and femur and act as shock absorbers.
Partial Knee Replacement Candidates
The best candidates for partial knee replacement—also known as unicompartmental knee replacement—are those whose osteoarthritis is limited to either the medial compartment or the lateral compartment, but especially the medial. If your knee pain is in the front—the patellofemoral compartment—a total knee replacement may serve you better.
Additionally, patients best suited for partial knee replacement include those who:
- Do not also have a form of inflammatory arthritis, such as rheumatoid arthritis
- Have an intact ACL
- Have good knee stability and range of motion
Partial vs. Total Knee Replacement
Having a partial knee replacement instead of a total knee replacement can grant a number of advantages. To understand how a partial knee replacement is performed, it’s helpful to first look at how a total knee replacement is done.
In a total knee replacement, the articular cartilage and some bone are replaced by metal components, the underside of the patella is resurfaced with plastic and the menisci are replaced by plastic spacers. A partial knee replacement works similarly, except that only the damaged side (lateral or medial) articular cartilage and meniscus are replaced, and the patella is typically not resurfaced.
A partial knee replacement offers a number of advantages, including:
- Less blood loss
- Less pain after surgery
- Shorter hospital stay
- Shorter recovery time
A partial knee replacement is usually more cost effective as well. Additionally, many of my patients tell me that since they keep more of their original knee anatomy in a partial knee replacement, their knees feel more natural and less mechanical than if they’d had a total knee replacement.
Partial Knee Replacement Drawbacks
Despite all the advantages of a partial knee replacement, it does have a few disadvantages. First, while it is a very effective surgery, there is a slightly greater chance that it won’t alleviate your pain. Second, you may end up needing a total knee replacement down the road if your knee osteoarthritis gets worse and begins to affect other knee compartments.
After Your Surgery
Because a partial knee replacement uses smaller incisions and causes less trauma to the knee than a total knee replacement, your recovery will likely be quicker. Patients generally can leave the hospital or surgery center one to three days after the surgery, though some can go home the same day.
Most people can walk without a cane, walker or crutches after about three or four weeks. Physical therapy should begin very soon after surgery and may need to continue for up to six months.
If you have stubborn knee pain that just won’t go away, I can help. Request an appointment today with me or one of my colleagues to learn more about your treatment options and see if you are a candidate for either a partial or total knee replacement.